1. Field of the Disclosure
This disclosure generally relates to an exhaust gas recirculation (EGR) system for an internal combustion engine.
2. Description of the Related Art
In Patent Document 1 is disclosed a cooling system of EGR for an internal combustion engine in which an EGR control during a quick acceleration may be effectively performed. Specifically, an estimate or virtual EGR rate is calculated based on a pressure difference across an EGR valve. In addition, a target EGR rate is calculated from engine rotational speed. A difference between the virtual EGR rate and the target EGR rate is used to correct an EGR valve opening.    [Patent Document 1] Japanese Unexamined Publication of Application 2004-150343, which has a corresponding U.S. Pat. No. 6,868,329 to Ito et al.